Problem: If $5a + b = -7$ and $2x + 2y = 7$, what is $4b + 20a + 14y + 14x$ ?
Answer: $= 20a + 4b + 14x + 14y$ $= (4) \cdot (5a + b) + (7) \cdot (2x + 2y)$ $= (4) \cdot (-7) + (7) \cdot (7)$ $= -28 + 49$ $= 21$